Draft Title: Comparison of Soil Responses to Long-Term Fertilization and Short-Term N and C Amendments in Miscanthus and Corn
Running title: fertilization effects on miscanthus List of Authors: Jaejin Lee,1,2 Paul Villanueva,1,2 Kate Glanville,1,2 Andy Vanloocke,1,2 Wendy Yang,1,3 Angela Kent,1,3 Marshall McDaniel,1,2 Steven Hall,1,2 Adina Howe ([email protected])1,2
Institutional affliation: 1DOE Center for Advanced Bioenergy and Bioproducts Innovation; 2Iowa State University; 3University of Illinois Urbana-Champaign
Contact Information: Adina Howe, [email protected], 515-294-0176
Proposed submission to: GCB-Bioenergy
Abstract (300 words) – needs shorteend Understanding the role of bioenergy crops in carbon and nitrogen dynamics is crucial for sustainable production of biofuels and bioproducts. Miscanthus x giganteus, a promising perennial biomass crop, is favored due to its high biomass yields compared to annual crops like maize. However, the effects of miscanthus on carbon sequestration and reducing nitrogen leaching and emissions compared to corn have been inconsistent. Additionally, the effects of long-term and short-term nitrogen management on miscanthus are under studied. In this study, we directly compared soils from miscanthus and maize fields for greenhouse gas emissions, net nitrogen mineralization, and the abundance of microbial nitrogen cycling genes over a 150-day soil incubation period. We evaluated these soil responses to compare the impacts of legacies of fertilization to the responses of contemporary amendments. Our results revealed that cumulative soil N2O emissions increased during the incubation, with miscanthus producing significantly greater N2O than corn. Additionally, higher fertilization levels resulted in greater N2O production, with nitrogen amendment showing a larger effect than carbon amendment. Net nitrogen mineralization was significantly affected by crop type and amendment but not historical fertilization. The abundance of specific bacterial genes involved in nitrogen cycling varied, with higher copies of genes associated with nitrification in miscanthus soils and an increase with historical fertilization levels. Genes encoding nitric oxide reductases generally decreased with higher nitrogen fertilization levels. We found that contemporary nitrogen addition increased N2O production as expected, but the larger difference in N2O production was explained by the legacy of fertilization. This trend was observed in both corn and miscanthus but significantly supported only in miscanthus, indicating a unique response of miscanthus to fertilization legacy. Overall, our results suggest that microbial processes in miscanthus soils differ significantly from maize and emphasize the importance of considering previous land management history when evaluating the contribution of miscanthus and bioenergy crops to nitrogen balances.